indicator light for stand-by status?

[pula58]

Someobody wants me to put an indicator light in their amp that shows the stand-by status (lamp off when in standy, lamp is on when amp fully power -up), in addition to the more standard power (mains) indictator lamp.


I can't think of a simple way to do this. Seems like powering the lamp off of the DC supply would mean burning wattage across a resistor to bring down the voltage to 6V or so.

Am I blind to an easy, simple, cheap way to do this?


Noticeable is the fact that I have not seen many (if any) amps with two power indicator lights One for mains, one for stand-by).

Any thoughts on this welcome!

[XgamerGt03]

Are you breaking a single HT wire after the rectifier, or are you breaking both wires. If you are using a DPDT switch and only breaking one wire then you have a pretty easy way to do it.

The second set of contacts on that DPDT switch can be used to turn an indicator lamp on or off. You would just wire it so that the lamp is on when the HT is broken.

What I would do if running the indicator off of 120VAC is run the hot to the switch and then from the switch connector opposite of the HT tap to the indicator, and keep the return always connected. Not too sure if you will have noise issue with this or not though.

If you are breaking both wires then you would need a 3PDT switch to do this.

[diagrammatiks]

you can power the power on light from the heater winding and you can power the other light off of a voltage divider and regulator off of the b+ line.

if you have a heater elevation divider off the b+ then it's even easier since you can just divider that down further.

[Jana]

Why not put an LED with the appropriate dropping resistor in the B+? The LED will then indicate if there is B+ or not.

[selloutrr]

seems dangerous. We have trained ourselves to think that standby is on when lit. if it's reversed I can see trouble.

if you must do it. why not use a 6.3v jewel light like fender. power it on the heater voltage and call it a day?

[pula58]

I thought about powering an LED off of the the filtered DC supply. But, if the LED uses, let's say, 20mA of current, with, say, 400V DC voltage, then that would be 0.02 * 400 = 8W !!!! So, you would need an 8W resistor between the 400V and the diode. This seems wasteful to me!

[diagrammatiks]

you wouldn't run it from 400v.

you'd tap off 6v for the light.

[eddie25]

seems dangerous. We have trained ourselves to think that standby is on when lit. if it's reversed I can see trouble.

if you must do it. why not use a 6.3v jewel light like fender. power it on the heater voltage and call it a day?

I think he is saying he wants a standby light in addition to the mains light, so there would still be a light on when in standby.

I think it's a pretty good idea actually, although superfluous. It would be awesome if you had a single light that was one color when in standby and another when in play.

[da Geezer]

Crate used a lighted rocker switch on some amps (VC30, schem linked). Take a look @ that circuit for ideas.........

http://www.el34world.com/charts/Schemat ... weramp.pdf

G

[img:400:300]http://www.vintageguitaramplifiers.net/ ... 982670.jpg[/img]

[rdjones]

The Traynor YBA3 Custom Special has two pilot lights, one green for "operate" and one red for "standby".
They are switched by a DPDT standby switch and powered off the 6.3V filament winding.

reddog

[Tillydog]

Just another idea for you:

In a little amp I built, I used a 2 colour LED inside an indicator lamp housing - Green on / amber standby.

It was powered from the heater supply and switched with a spare pole of the standby switch (it's the large 'eye' on the right):

[IMG3008]http://i255.photobucket.com/albums/hh14 ... C_9052.jpg[/img]

0.02p

Andy

[da Geezer]

The Traynor YBA3 Custom Special has two pilot lights, one green for "operate" and one red for "standby".
They are switched by a DPDT standby switch and powered off the 6.3V filament winding.

reddog

O yeah, I like that configuration.....very cool, & very simple, using only one switch. And, you can use any type or color of lights you wish.

Tillydog's method is also a cool option!

G

[Phil_S]

Interesting comments. It seems the answer is, it could be done. It begs the whole question about standby. Newer wisdom suggests it's not needed. See what the Valve Wizard says: http://www.freewebs.com/valvewizard1/standby.html

Tell the customer you'll remove the standby all together and then he won't need to concern himself with whether there is a light on it or not!

[mlp-mx6]

Use a DPDT switch for standby and use the "other side" of that switch to turn on the "off standby" light.

If you must have a standby...

[VacuumVoodoo]

If you must have an illuminated standby switch the light should indicate presence of the B+ voltage. Anything else makes no sense to me.